Washing machine agitator cap



Dec. 13, 1955 w. A. FRANTZ WASHING momma AGITATOR CAP Filed Aug. 28, 1952 INVEN TOR. WAL TEE A. FEANTZ United States Patent WASI-HNG MACHINE AGITATOR CAP Walter August Frantz, Shaker Heights, Ohio, assignor to Tinherman Products, Inc., Cleveland, Ohio, :1 corporation of Ohio Application August 28, 1952, Serial No. 306,858

3 Claims. (Cl. 287-53) The present invention relates to improvements in washing machine agitator caps. In the usual agitator type washing machine, a hollow agitator is mounted within the tub about a vertical agitator drive shaft journalled in and supported by a center post, the top portion of the agitator and the 'top end of the shaft being provided with structures whereby the agitator is mounted on the shaft in proper position within the tub. Since the agitator is frequently removed for cleaning the machine after use, the means by which the agitator is mounted to the shaft must allow ready removal and replacement of the agitator in proper position. Generally a tapered agitator mounting block of non-circular cross section is provided on the drive shaft end to engage a complementary formation in the agitator, and a bolt type agitator cap, threaded axially into the top of the shaft or mounting block with head bearing on the agitator, holds the agitator in place.

Whatever the structure used, it is of course necessary that the agitator be firmly secured to the shaft, particularly in the more recent designs where the means mounting the agitator to the shaft end is the sole means of maintaining the agitator in correct .position. As many housewives cannot, or at least do not, exert 's'uificient torque on the usual bolt type agitator cap in replacing the agitator, the agitator often loosens during operation of the washer, leading to undue wear in the mounting structures or tangling of clothes beneath the agitator when it rides up a distance sutficient to permit clothes to pass between the agitator and tub bottom. Use of a lock washer between the head of the clamping bolt and the agitator, though it might prevent loosening of the bolt during the oscillating operation of the agitator, is not satisfactory because of the likelihood of loss of the washer, scoring and wearing of the adjacent parts due to frequent removal, and the general disadvantage of having another loose part when the agitator is removed.

The object of the present invention is the provision of a washing machine agitator cap or clamping structure which maintains the necessary clamping force and is readily tightened to a sufiicient degree without requiring the application of great force. Another object is the provision, in a clamping structure of the character above described, of a clamping bolt structure having the general functional characteristics of the combination of a bolt and lock washer.

Other objects and advantages of the invention will appear from the following description and the drawings thereof wherein- Fig. 1 is a vertical axial section through the agitator cap of this invention in the environment of its use in a washing machine, with only the top portions of the agitator, agitator shaft and center post of the washing machine being shown;

Fig. 2 is a top plan view of the cap with a portion broken away to show the structure more clearly; and

7 2,726,888 Patented Dec. 13, 1955 Fig. 3 is a horizontal section taken along the line 33 in Fig. l. V

In the drawings appears a typical arrangement of a center post 10, agitator shaft 11, agitator mounting block 12 and agitator 13, with only those portions of these elements being shown which are necessary to show the use of this invention in the usual agitator type of washing machine. The hollow vertical center post 10 is disposed within the tub of the machine with its bottom secured in sealed relation to the tub bottom and with its top extending above the maximum operating water level. The agitator shaft 11, for which bearing means are provided in the center post, is connected at its lower end to a transmission and reversing mechanism located beneath. the washer tub. An agitator mounting block 12, having a bore 14 to receive the upper end of shaft 11 and secured thereto by a press fit as shown in the drawings or by set screws or other apt means, serves to mount the agitator in co-axial relation to the shaft and post. The agitator comprises a hollow cylindrical upper portion 13 providing a hub from which depends a downwardly and outwardly flaring roughly coniform hollow body or skirt provided with fins or projecting blades.

The interior of the upper end of the hub 13 and exterior of the mounting block 12 are formed with com plementary tapering surfaces, preferably non-circular in horizontal cross-section and symmetrically disposed relative to the axis of shaft. Thus the mounting block 12 has a truncated pyramidal portion 16 of rectangular horizontal section fitting into the correspondingly shaped portion 17 of the agitator hub 13, whereby the agitator is driven in its oscillating rotary motion Without slippage relative to the shaft. The tapered portion of the hub, however, extends somewhat beyond the end of the block 12. When the hub is firmly seated on the block. the tapered relation of the parts insures positioning of the agitator body in co-axial relation to the shaft with proper clearance relative to the center post despite wear attendant upon repeated removal and replacement of the agitator and without the use of any type of bearing between center post and the lower part of the agitator body. To maintain the agitator in firmly seated relation on the mounting block during operation of the washer, the end of the latter is axially bored and threaded at 18 and an agitator cap with the head thereof bearing on the end of hub 13 is screwed into the block to draw the tapered parts of the block and hub together.

The agitator cap or clamping device comprises a body or head member 19; a bolt 20 with the head 21 disposed within a cavity 22 formed in the body and with the threaded shank 23 extending through a central aperture 24 in the bottom wall of the body; a relatively stifi compression spring element 25 disposed about the bolt shank between the bolt head and the bottom of the cavity; and a Welsh plug 26 or other means closing the top of the cavity. The body member 19 is provided at its periphery with a knurled or notched portion 27 whereby it may be turned manually without slippage. The bottom of the body has a flat portion 28 to provide a clamping bearing surface abutting the end of the hub 13.

The cavity 22, shown square to correspond to the shape of the bolt head 21, may be of any shape providing rotational purchase on the bolt head and allowing axial movement of the bolt to compress spring 25. Preferably the size of aperture 24 and cavity 22 are such as to allow some floating of the body relative to the bolt so that the bottom of the body bears evenly on the end of hub 13 as the cap is screwed down thereon. The spring element 25 shown in the drawings is a convolute or spiral wound steel strip or ribbon with its turns axially displaced to form a conical helical spring resistring compression as the bolt advances parallel to the axis of the spiral. Other forms of means may of course be used.

With this structure, as the clamping device is screwed into place, after initial contact with the end of hub 13, further turning is possible against a constantly increas ing resisting force as the bolt head compresses the spring means in' an axial direction and as an increasing clampingforce bears on the hub end. Reverse relations obtain as the cap is unscrewed. Whereas with the ordinary hand bolt a slight unscrewingmovement of the bolt results in a great decrease in the clamping force and consequent looseness of the agitator'which rapidly increases during oscillation of the agitator, a much spring or elastic greater movement is required to attain the same drop in clamping force with the present structure so, that there is a self-locking action with little likelihood of such loosening.

I claim: 7

1. In a washing machine having an agitator drive shaft: an agitator mounting assembly comprising an externally tapered axially bored and threaded agitator mounting block adapted to be carried on the agitator drive shaft of the machine, a hollow interiorly tapered hub portion on the agitator fitted to said tapered mounting block, and self-locking clamping means engaging said mounting block and bearing endwise on said hub portion; said clamping means including a hollow body member having a centrally apertured bottom wall bearing on the end of said hub portion, a bolt extending through the aperture of said bottom wall and axially movable relative to said body member threaded into the axial bore of said mounting block, the head of said bolt being disposed within said hollow body member and engaged thereby against relative rotation, and compression spring means disposed within said hollow body memberbetween and bearing upon the bolt head and said bottom wall to resist downward axial movement of the bolt relative to said body member.

2. A self-locking bolt comprising a head member having a cavity therein, abottom wall providing a bearing surface for clamping an element secured by the bolt,

and an aperture in the bottom wall of the head member opening to said cavity; an externally threaded member extending through said aperture and axially movable relative to the head member and including a head portionrigidly fixed thereon disposed within said cavity, said threaded member and said head member being mutually so shaped in cross section as to prevent relative rotation therebetween; and elastic means disposed between and bearing upon the head portion of said threaded member and the bottom wall of said cavity opposing axial movement-of said head portion toward the bottom of the cavity.

'3. A self-locking bolt adapted for manual tightening comprising a head member having 'a bottom wall providing a clamping surface for bearing against an object secured thereby, said head member having 7 a cavity therein and a central aperture in the bottom wall of the head member opening to said cavity, said head member having an external form whereby it may be firmly grasped manually for manipulation; an externally threaded member extending through said aperture and including a head portion "rigidly afiixed ,thereon disposed within said cavity, said head. portion of the threaded member having engagement with said head member against relative rotation and being ,free .for limited axial movement relative to said head member While maintaining such engagement therewith, and compression spring means disposed between and bearing upon the head portion of said threaded member and the bottom wall of said cavity resisting axial rnovementof said head portion toward the bottom of said cavity, said compression spring means comprising a spring metal strip convolutely wound to form a conical helical spring.

References Cited in the file of this patent UNITED STATES PATENTS 

